Investigating the effect of anxiety on pain scores in dogs

To investigate the relationship between anxiety and pain scores using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) in dogs.

Prospective observational study.

A group of 18 dogs undergoing surgical management of stifle disease.

Preoperatively dogs were scored using the CMPS-SF, the anxiety behaviour-based Reactivity Evaluation Form (REF), a Visual Analogue Scale (VAS) for anxiety and a sedation score. Assessments of pain, anxiety and sedation were repeated approximately 2-6 hours postoperatively. Dogs were divided into groups based on preoperative REF ('Low REF' and 'High REF'), and VAS scores ('Low VAS' and 'High VAS'). Scores (CMPS-SF, REF, VAS and sedation) were compared between groups using Mann-Whitney U tests. Preoperative and postoperative CMPS-SF, REF and VAS scores were compared using Wilcoxon signed-rank tests. Relationships between anxiety and CMPS-SF scores were assessed using a Spearman rank correlation coefficient. Scores are presented as median (range). A p value of < 0.05 was considered significant.

When divided based on REF, CMPS-SF scores did not differ between groups preoperatively [Low REF: 2 (0-3), High REF: 2 (1-3); p = 0.509] or postoperatively [Low REF: 3 (2-5), High REF: 3 (2-5); p = 0.624]. When divided based on VAS, CMPS-SF scores did not differ between groups preoperatively [Low VAS: 2 (0-2), High VAS: 2 (1-3); p = 0.215] or postoperatively [Low VAS: 3 (2-5), High VAS: 3 (2-5); p = 1]. Postoperative REF [pre: 4.5 (2-8), post: 5 (4-10); p = 0.0105] and CMPS-SF scores [pre: 2 (0-3), post: 3 (2-5); p = 0.0318] increased significantly compared with preoperative scores.

No apparent relationship exists between baseline anxiety levels and CMPS-SF scores. Understanding the influence of anxiety when using the CMPS-SF is important when assessing pain in dogs. Anxiety and pain may increase postoperatively in dogs undergoing orthopaedic surgery.